Rocker arm

ABSTRACT

Rocker arm for actuating at least one gas exchange valve of an internal combustion engine having an elongated lever body ( 2 ) with a floor ( 3 ) and with side walls ( 4,5 ) angled away therefrom, wherein a first end section ( 6 ) of the lever body ( 2 ) has a cup ( 9 ) for a support element formed in the floor ( 3 ), and in that a section ( 7 ) near the center is provided with a cam engagement surface and in that a second end section ( 8 ) of the lever body ( 2 ) has a contact surface ( 12 ) for a valve stem end of the gas exchange valve, wherein a crossbar ( 13 ) extends between the section ( 7 ) near the center and the second end section ( 8 ), wherein the crossbar ( 13 ) has a stamping  14 ) that is provided on the side facing away from the section ( 7 ) near the center.

FIELD OF THE INVENTION

The invention concerns a rocker arm for actuating a gas exchange valveof an internal combustion engine.

BACKGROUND OF THE INVENTION

In internal combustion engines, rocker arms are located in a valve trainas transmission elements between cams and the gas exchange valves to beactuated. Rocker arms consist of a lever body that is supported at oneof its ends on a support element and with its other end engages, througha contact surface, the gas exchange valve to be opened. In a section ofthe lever body near the center, a cam pickup surface is provided onwhich a cam of a camshaft runs during operation of an internalcombustion engine, causing a pivoting motion of the rocker arm. The campickup surface can be implemented as a sliding surface or as a camroller.

A rocker arm for actuating a gas exchange valve of an internalcombustion engine is known from DE 10 2008 029,333 A1. At one end, therocker arm has an oval opening that encompasses a valve stem end of thegas exchange valve. In addition, the rocker arm provides a cam roller ina section near the center.

WO2011/157499 A1 discloses a rocker arm that has a cam roller supportedon an axle pin by means of a needle roller and cage assembly. A contactsurface for a valve stem end of the gas exchange valve is provided atone end of the rocker arm. Side bars are provided in the region of thecontact surface to guide the rocker arm on the valve stem end.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a rocker arm that canbe manufactured economically and that ensures adequate stiffness.

According to the invention this object is attained by a rocker arm foractuating at least one gas exchange valve of an internal combustionengine having an elongated lever body with a floor and with side wallsangled away therefrom, wherein a first end section of the lever body hasa cup for a support element formed in the floor, and in that a sectionnear the center is provided with a cam engagement surface and in that asecond end section of the lever body has a contact surface for a valvestem end of the gas exchange valve, wherein a crossbar extends betweenthe section near the center and the second end section and wherein thecrossbar has a stamping that is provided on the side facing away fromthe section near the center.

In the rocker arm according to the invention, the crossbar is providedwith a stamping. The stamping can be an embossing, for example. Thestamping in the crossbar makes it possible to avoid contact between thevalve stem end and the lever body during pivoting motions of the rockerarm. The necessary stiffening of the rocker arm is ensured by thecrossbar, which in turn results in increased strength of the rocker arm.

In a preferred embodiment of the invention, the shape of the stamping ismatched to the valve stem end. This means that the shape of the stampingis designed to be complementary to the shape of the valve stem end.Preferably the stamping is implemented as a cylindrical molding.

Preferably the second end section of the lever body has a W-shapedprofile when viewed in cross-section. As a result of the W-shapedprofile, the side bars known from the prior art that would be necessaryfor valve guidance are eliminated. This has the advantage that theweight of material used can be reduced, and thus the production costscan be decreased. The W-shaped profile preferably is open in thedirection facing away from the gas exchange valve. However, a reversedarrangement of the W-shaped profile is also possible.

In another embodiment of the invention, a distance between alongitudinal center of the cup and a center of rotation of the campickup surface is half as large as or less than half a distance betweenthe longitudinal center of the cup and a center of a contact region ofthe gas exchange valve at the contact surface. Accordingly, the campickup surface can be positioned close to the contact region of the gasexchange valve. This has the advantage that the overall length of therocker arm can be shortened to achieve a compact component.

In one embodiment, the cam pickup surface is implemented by a camroller, and the section near the center has a recess in the floor thatserves to accommodate the cam roller. The recess in the floor createsthe necessary free space for the cam roller so that rotary motion of thecam roller is possible.

Preferably, the lever body is either produced by stamping and formingtechniques from a sheet metal material, or by extrusion molding.However, other materials and manufacturing methods are also possible.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is explained below using threefigures.

They show:

FIG. 1 a rocker arm according to the invention in a perspective view,

FIG. 2 a bottom view of the rocker arm according to the invention, and

FIG. 3 a longitudinal cross-section through the rocker arm according tothe invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 each show different views of a rocker arm 1 according tothe invention. The rocker arm 1 has an elongated lever body 2, which hasa floor 3 and side walls 4, 5 angled away therefrom. The floor 3 and theside walls 4, 5 form a W-shaped profile when viewed in cross-section.Moreover, the lever body 2, which is made of a sheet metal material, isdivided into a first end section 6, a section 7 near the center, and asecond end section 8.

Formed in the part of the floor 3 running along the first end section 6is a cup 9, which rises between the side walls 4, 5. The cup 9 providessupport on a support element that is not shown.

In the region of the section 7 near the center, each of the side walls4,5 has a bore 10 serving to support a cam roller that is not shown. Thecam roller that is not shown defines a cam pickup surface. A recess 11designed with a rectangular outer contour is provided in the part of thefloor 3 running along the section 7 near the center.

A contact surface 12 for a valve stem end, not shown, of a gas exchangevalve is provided on the part of the floor 3 running along the secondend section 8 of the lever body 2. A crossbar 13 that is providedbetween the side walls 4,5 extends between the second end section 8 andthe section 7 near the center. The crossbar 13 has a stamping 14, whichis implemented as a cylindrical molding, on the side facing away fromthe section 7 near the center. The stamping 14 makes it possible foradequate clearance of the contact surface relative to the gas exchangevalve, not shown, to be present during pivoting motions of the rockerarm 1.

FIG. 3 shows a longitudinal cross-section through the rocker arm 1according to the invention. This illustrates the relationship of theindividual sections to one another. In the first end section 6, the cup9 has a longitudinal center 15. Each of the bores 10 has a center point16 that defines a center of rotation 17 for the cam pickup surface. Thecontact surface 12 defines a contact region 18 of the gas exchangevalve, not shown.

A distance L1 is defined between the longitudinal center 15 of the cup 9and the center of rotation 17 of the cam pickup surface. A distance L2is defined between the longitudinal center 15 of the cup 9 and a centerof the contact region 18 of the gas exchange valve. The distance L1 hereis half as large as or less than half the distance L2. This distanceratio makes possible a short, compact lever body 2.

LIST OF REFERENCE CHARACTERS

-   1 rocker arm-   2 lever body-   3 floor-   4 side wall-   5 side wall-   6 first end section-   7 section near the center-   8 second end section-   9 cup-   10 bore-   11 recess-   12 contact surface-   13 crossbar-   14 stamping-   15 longitudinal center of the cup-   16 center point-   17 center of rotation-   18 contact region of the gas exchange valve-   L1 distance-   L2 distance

1. Rocker arm for actuating at least one gas exchange valve of aninternal combustion engine having an elongated lever body (2) with afloor (3) and with side walls (4,5) angled away therefrom, wherein afirst end section (6) of the lever body (2) has a cup (9) for a supportelement formed in the floor (3), and in that a section (7) near thecenter is provided with a cam engagement surface and in that a secondend section (8) of the lever body (2) has a contact surface (12) for avalve stem end of the gas exchange valve, wherein a crossbar (13)extends between the section (7) near the center and the second endsection (8), characterized in that the crossbar (13) has a stamping (14)that is provided on the side facing away from the section near thecenter (7).
 2. Rocker arm according to claim 1, wherein a shape of thestamping (14) is matched to the valve stem end.
 3. Rocker arm accordingto one of the preceding claims, wherein the second end section (8) ofthe lever body (2) has a W-shaped profile when viewed in cross-section.4. Rocker arm according to one of the preceding claims, wherein adistance (L1) between a longitudinal center (15) of the cup (9) and acenter of rotation (17) of the cam pickup surface is half as large as orless than half a distance (L2) between the longitudinal center (15) ofthe cup (9) and a center of a contact region (18) of the gas exchangevalve at the contact surface (12).
 5. Rocker arm according to one of thepreceding claims, wherein the cam pickup surface is implemented by a camroller, and wherein the section near the center has a recess (11) in thefloor that serves to accommodate the cam roller.
 6. Rocker arm accordingto one of the preceding claims, wherein the lever body (2) is eitherproduced by stamping and forming techniques from a sheet metal material,or by extrusion molding.